The preparation of substituted amido phthalocyanine derivatives is well known and is described in GB 844,419 and more recently EP 0519395.
The multi-step prior art process for the production of substituted amido phthalocyanine derivatives start from the well known carboxamide of phthalocyanine. The phthalocyanine carboxamide is manufactured from a substituted phthalic acid derivative or anhydride derivative, namely trimellitic acid or anhydride. The trimellitic acid is reacted with phthalic acid or anhydride in the presence of urea, copper salt, and ammonium molybdate either in the presence of a high boiling organic solvent such as nitro benzene or ortho nitro toluene, or using excess urea as the solvent for the reaction. The ratio of trimellitic acid and phthalic acid can vary depending on the desired substitution level of the phthalocyanine carboxamide. The reaction mixture is heated at 180-250.degree. C. for approx 4-20 hours. The reaction product thus obtained can be further purified by dilute aqueous acid wash, or by conventional acid pasting to yield a phthalocyanine carboxamide which is normally 90% pure.
The next stage of preparation is to hydrolyse the resulting amide to the acid followed by reaction of the acid group with sulphonyl chloride to produce the corresponding acid chloride. The final step in the synthesis of the amindo 755 phthalocyanines is the reaction of the acid chloride with the relevant amine.
EP0519395 describes a number of these substituted amido phthalocyanines wherein the amido substitution has a maximum of n=2, at the same time it describes the production of these derivatives from the prior art method and their use as phthalocyanine dyes and their effect in optical recording elements.
It has now been found that substituted amido phthalocyanine derivatives may be readily prepared from phthalocyanine carboxamide by reaction with amine/acid salts. This novel process involves less reaction steps than the prior art process and provides substituted amido phthalocyanine derivatives in high yield.